Web Application Firewall
Definition
Security service that protects web applications from common attacks like SQL injection, cross-site scripting, and other web-based threats.
Use Cases
- Cloudflare: Protecting high-traffic customer websites from OWASP Top 10 attacks and automated bot abuse — Cloudflare operates a globally distributed WAF at the edge, using managed rule sets, custom rules, and bot management signals to filter malicious HTTP requests before they reach origin servers. (Reduced malicious traffic reaching customer origins, improved site availability during attack spikes, and lowered operational burden by blocking common exploits automatically.)
- Amazon: Protecting public-facing retail and API endpoints from injection attacks and request floods — Amazon teams use AWS WAF with AWS edge and load balancing services, combining managed rule groups (e.g., common vulnerabilities) with rate-based rules and IP reputation controls to block abusive patterns. (Improved resilience of customer-facing endpoints by filtering malicious requests early and reducing the risk of web-layer exploits impacting availability or data integrity.)
- Microsoft: Shielding web applications from common web exploits and layer 7 attacks — Microsoft uses Azure’s web security capabilities across its cloud ecosystem; Azure WAF is commonly deployed with Azure Front Door and Application Gateway to enforce managed rules and custom policies for HTTP(S) traffic. (Stronger protection against common web threats and more consistent security controls at the application entry points.)
Provider Equivalents
- AWS: AWS WAF
- Azure: Azure Web Application Firewall (Azure WAF)
- GCP: Cloud Armor
- OCI: OCI Web Application Firewall
Frequently Asked Questions
- What's the difference between a Web Application Firewall (WAF) and a network firewall?
- A network firewall mainly controls traffic based on IP addresses, ports, and protocols (layers 3–4). A WAF focuses on HTTP/HTTPS traffic (layer 7) and understands web requests, so it can block attacks like SQL injection, cross-site scripting (XSS), malicious bots, and suspicious request patterns that a network firewall may not detect.
- When should I use a Web Application Firewall (WAF)?
- Use a WAF when you run any internet-facing web app, API, or login/checkout flow—especially if it handles personal data, payments, or accounts. It’s particularly useful when you need quick protection against common web exploits, want to reduce bot abuse (credential stuffing, scraping), or need to enforce consistent security rules in front of multiple apps.
- How much does a Web Application Firewall (WAF) cost?
- Costs vary by provider and are usually driven by (1) number of protected resources/policies, (2) number of rules or managed rule sets enabled, and (3) request volume inspected (often priced per million requests). Extra features like bot management, advanced DDoS protection, logging, and custom rule processing can add cost. For accurate estimates, model expected monthly request counts and which managed rule sets/features you need.
Category: security
Difficulty: intermediate
Related Terms
See Also